Canucks throw in a 4th in 2022 to wings

No

You're dreaming if you think 10 games of Pearson is worth a B level prospect and a 2nd.

& Buffalo can easily make that deal at the deadline with Colorado and not need Vancouver as the middle man, and get more for Hall.

You may need to look closer. Colorado doesn’t have the cap space. Both Buffalo and Van are retaining to get the deal done.

That's more than a reasonable asking price.
Last year's trade deadline
Toffoli (no retention) for Schaller (1.9M) + Madden (top/mid prospect) + 2020 2nd rounder

You may need to look closer. Colorado has $3.4M in deadline cap space and Hall's deal is prorated at $1.8M at full salary. Even if Buffalo retains 50% it's only $900K

Schaller was cap a dump, that's why Vancouver paid more

A 1.9M dollar contract at the deadline doesn’t cost too much to move as the contract is prorated.

It's still a cap dump when the player isn't worth the contract and the team had to take it for the deal to work

Yes but the value to dump them is based on cap hit and actual cash which is minimal in this case as it’s prorated. Let’s say it’s a fifth to dump that max considering Toronto retained like 2.5M on Lehner for a 5th at the TDL.

So why wouldn't the deal the OP posted equate to the Toffoli deal?
OP is willing to take 50% retention of Pearson plus take Vesey's money for a 2nd and B prospect

And add to that...with the way the Leafs are playing in the reg season that will be a late 2nd pick.

Vesey's "money" is virtually nothing. It's a little over $200K at the deadline and his contract is fully able to be buried on the taxi squad or minors, so they have no need to move him.

The pick isn't the issue, the prospect is. Leafs trading for anyone at the deadline gets them 10-15 games of a player. Pearson is a third line player on the Leafs, it's definitely not worth giving up a quality prospect for that few of games for a third liner. Especially for someone that isn't a massive upgrade in the playoffs.

Prospects will be more valuable this year than ever due to the taxi squad and no needs for waivers. Not giving up on a good one for a guy that doesn't meet the need of the team.

As much as this is an interesting AGM, you can only retain salary on three players so it’ll take a lot of work to try to rid themselves of those contracts.

The amount of games is irrelevant. It would be proportional to the amount of games played if this wasn't a shortened season. Pearson may be relegated to third line duties on the Leafs but his ability to play up and down the line-up, his playoff experience is a huge boost and asset to the Leafs. Especially, since they're sitting pretty in the standings right now, this is a once in a lifetime opportunity of playing in a weaker division.
If Pearson is being traded straight up at the deadline he would be worth a 2nd round pick. The fact the Canucks are taking on Vesey's salary (how minuscule it may be) but most importantly agreeing to retain 50% of Pearson's contract should garner a prospect.